Developed land for housing, a road, a dam, or the like is constructed by banking or cutting, and a slope thus formed is eroded by rainfall, weathering, or the like if left with no treatment, causing an accident such as a landslide and a rockslide. To cope with the situation, in PTL 1, soil erosion is prevented by spraying, on a slope, a spray material formulated with a soil drying inhibitor composed of a water-swelling and water-absorbing resin, a surfactant, and a synthetic resin emulsion at a ratio from 0.5 to 1.5 kg per 1 m3 of a spray material.
Meanwhile, since the synthetic resin emulsion used in PTL 1 is in a liquid state, it has problems of freezing and costs for transportation. To solve such problems, PTL 2 discloses a technique of using resin powder produced by drying a synthetic resin emulsion as a soil erosion inhibitor.